The present invention relates to an electromagnetic interference suppressing body for use in suppressing electromagnetic interference by any useless or undesired electromagnetic wave or waves, and also relates to an electric circuit device using the electromagnetic interference suppressing body.
In digital and/or high frequency electric circuit devices, small size and light weight are strongly desired and, therefore, electronic parts are required to be mounted on a printed circuit board as well as in an electric circuit device with a high density.
When electronic parts and wiring conductive lines are mounted on a circuit board, electromagnetic interference is caused by electrostatic and/or magnetic coupling between electronic parts and/or wiring conductive lines. Further, if a plurality of circuit boards are disposed adjacent to one another, electromagnetic interference is also caused between the adjacent circuit boards. In particular, the electromagnetic interference is severe when active elements such as semiconductor devices are mounted on the circuit board or boards because the active elements radiate undesired electromagnetic wave or inductive noise.
In the prior art, suppress of the electromagnetic interference was tried by means of connecting a low-pass filter or noise filter to each output terminal of the circuit board or by means of keeping a circuit in question at a distance. However, they require a space for disposing the filter or filters and/or a space for giving the distance. As a result, the device is made large in size and weight.
For suppressing electromagnetic coupling between adjacent circuit boards, a conductive shielding member was disposed between the circuit boards. However, the shielding member cannot prevent reflection of an undesired radiation from one circuit board, so that the reflection increases magnetic coupling between parts on the circuit board.
Hybrid integrated circuit elements are known as electronic circuit elements of a high density and a small size and are usually mounted on a mother board or boards in the electric circuit device. In the condition, the hybrid integrated circuit elements also suffer from electromagnetic interference.
Accordingly, it is an object of the present invention to provide an electromagnetic interference suppressing body with a low electromagnetic transparency and with a low electromagnetic reflection which enables to electromagnetically shield a circuit board from another circuit board adjacent thereto as well as to suppress reflection of undesired radiation by the body to thereby suppress coupling between parts on the same circuit board even without use of low-pass filter or noise filter and even without a large distance between parts of circuit boards.
It is another object of the present invention to provide an electric circuit device having an electromagnetic interference suppressing body with a low electromagnetic transparency and with a low electromagnetic reflection disposed in a space between an electronic circuit part and a circuit board to thereby suppress coupling between the circuit part and a wiring line on extending on the circuit board.
Further, it is an object of the present invention to provide a hybrid integrated circuit element wrapped by an electromagnetic interference suppressing body with a low electromagnetic transparency and with a low electromagnetic reflection which is enable to suppress electromagnetic interference caused by any external elements and by any internal elements.
According to the present invention, an electromagnetic interference suppressing body for suppressing electromagnetic interference by undesired electromagnetic waves can be obtained which comprises a conductive support element and a non-conductive soft magnetic layer overlying at least one of surfaces of the conductive support element.
Further, according to the present invention, an electronic equipment can be obtained which comprises a circuit board having an active element thereon, the active element generating an inductive noise, wherein an electromagnetic interference suppressing body is interposed between the circuit board and the active element, the electromagnetic interference suppressing body comprising a conductive support element and a non-conductive soft magnetic layer overlying at least one of surfaces of the conductive support element.
Furthermore, according to the present invention, a hybrid integrated circuit element can also be obtained which has a circuit board, an active element and a passive element mounted on the circuit board, and which is characterized in that the active element, the passive element, and the circuit board are covered together with and sealed by an insulating layer, a non-conductive soft magnetic layer comprising soft magnetic powder and organic binder, and overlying an outer surface of the insulating layer.